IVaids {dblcens}R Documentation

Data: AIDS patient among IV drug user

Description

Time to AIDS among 232 patients infected with HIV. 136 left AIDS-free (right censored). 14 died with AIDS without prior diagnoses (left censored). 82 had AIDS while in the program (non-censored).

Usage

 data(IVaids) 

Details

A date set with 232 rows and 7 variables.

"A doubly censoring scheme occurs when the lifetimes T being measured, from a well-known time origin, are exactly observed only within a window [L, R] of observational time and are otherwise censored either from above by R (right-censored observations) or below by L (left-censored observations).

Sample data consists on the pairs (U, delta) where U = min[R, max(T, L)] and delta indicates whether T is exactly observed (delta = 0), right-censored (delta = 1) or left-censored (delta = -1). We are interested in the estimation of the marginal behaviour of the three random variables T, L and R based on the observed pairs (U, delta)." —— quote from the below reference paper.

The definition of the censoring indicator, (delta), here is different from the one we use, (d), in the functions d011( ) and d011ch( ).

- (delta=0) corresponds to (d=1);

- (delta=1) corresponds to (d=0);

- (delta= -1) corresponds to (d=2).

Therefore we need to make the change before call the function d011( ) or d011ch( ).

"The data set is from a cohort of drug users recruited in a detoxification program in Badalona (Spain). For these data we may estimate the survival function for the elapsed time from starting IV-drugs to AIDS diagnosis, as well as the potential follow-up time." ——quote from the below reference paper.

The entry "AIDSDate-FIRST_IV" is the observed AIDS-free times, U, in the above definition. The unit of measurement is "days".

According to the paper the estimated median of U is 15.44 years. And at time of 10 years, the probability of AIDS-free is about 0.7. (from my reading of the plot from the paper, this probability is more closer to 0.75).

References

Julia, Olga and Gomez, Guadalupe (2011) Simultaneous marginal survival estimators when doubly censored data is present. Lifetime Data Analysis, July 2011, Volume 17, Issue 3, pp 347-372.


[Package dblcens version 1.1.9 Index]